Relationship between image quality of PET/CT in automatic tube current modulation and effective dose
Yitian Wu, Jianhua Geng, Zhaomeng Du, Gaochang Bi, Yonghe Qi, Chaokun Zhang, Rong Zheng, Ning Wu
Abstract
ObjectiveTo investigate the relationship between image quality of PET/CT in automatic tube current modulation and effective dose(ED) of patients and to determine the optimal acquisition scheme.
MethodsScanning was performed on anthropomorphic phantom RS-550 using GE Discovery ST-16 or Discovery Elite PET/CT. The same CT acquisition conditions was used: tube voltage 120 kV, pitch 1.375, rotation speed 0.8 s, noise index ranged from 8 to 30, interval 2, automatic tube current low limit 30 mA, high limit ranged from 200 to 350 mA, interval 50 mA. The images were analyzed, and the noise, signal to noise ratio (SNR) and figure of merit (FOM) of main organs in the abdomen were calculated. The relationship between image quality and ED was analyzed. Two-sample t test was used for data analysis.
ResultsThe noise of each organ decreased significantly along with the increase of ED until the ED of ST-16 increased to 15 mSv or Elite increased to 12 mSv, then the image noise decreased gently. SNR of each organ image increased along with the increase of ED. The FOM of liver decreased along with the increase of ED, while the FOM of other organs did not change significantly with ED. All image indicators of Elite PET/CT were better than ST-16 PET/CT at the same ED (5-20 mSv), though there was no significant difference (t: 0.133-4.701, all P>0.05). When ED was 5 mSv, the noise of liver with ST-16 was 12.0% (28.9 vs 25.8) higher than that with Elite, and the SNR and FOM of liver with Elite was 13.9% (4.1 vs 3.6) and 66.7% (0.50 vs 0.30) higher than that with ST-16, respectively.
ConclusionWhen the ED caused by the 2 PET/CT systems was between 5-20 mSv, the image quality is improved along with the ED increasing in a certain range.
Key words:
Photon-emission tomography; Tomography, X-ray computed; Radiation dosage; Abdomen; Manikins
Contributor Information
Yitian Wu
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Department of Nuclear Medicine, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Jianhua Geng
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Department of Nuclear Medicine, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Zhaomeng Du
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Gaochang Bi
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Yonghe Qi
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Chaokun Zhang
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Rong Zheng
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Department of Nuclear Medicine, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Ning Wu
Department of PET/CT Center, National Cancer Center, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
